Patent Literature 1 is a prior art slide rail device for vehicle, which is equipped with a pair of left and right lower rails which are fixed to a vehicle interior floor, extend in the forward/rearward direction, include a large number of lock grooves arranged in a forward/rearward direction; a pair of left and right upper rails which support a seating portion of a seat and are slidably supported by the left and right lower rails; lock springs, supported by the upper rails and each having a locking portion which is disengageably-engageable with the lock grooves from below; and lock-release levers, wherein each lock-release lever is rotatable between a locked position, at which the lock-release lever does not act on the lock spring that is supported by the upper rail, and an unlocked position, at which the lock-release lever acts on the lock spring to eject the locking portion from the corresponding lock groove.
In this slide rail device, when an occupant applies no operating force to the lock-release levers, the slide position of the seat and upper rails with respect to the lower rails is maintained by the locking portion of each lock spring engaging with one of the lock grooves. On the other hand, upon a passenger rotating the lock-release levers to the unlock position against the biasing force of the lock springs, the locking portion of each lock spring disengages from the lock groove to thereby allow the seat and the upper rails to slide with respect to the lower rails.
Whereas, a slide rail device for a vehicle disclosed in Patent Literature 2 is equipped with a pair of left and right lower rails which are fixed to a vehicle interior floor, extend in a forward/rearward direction and include a large number of lock grooves, arranged in the forward/rearward direction; a pair of left and right upper rails which support the seating portion of a seat and are slidably supported by the left and right pair of lower rails; a lock lever which includes a locking portion, which is disengageably-engageable with the lock grooves from below and is supported by each upper rail to be rotatable in the upward/downward direction between a locked position, at which the locking portion is engaged with the lock grooves, and an unlocked position, at which the locking portion escapes from the lock grooves; and a biaser which rotatably biases the locking lever toward the locked position.
In this slide rail device, when an occupant applies no operating force to the lock lever, the slide positions of the seat and the upper rails with respect to the lower rails are maintained since the locking portion of each lock lever which is held in the locked position by the biasing force of the biaser is engaged with some of the lock grooves. On the other hand, upon an occupant rotating the lock lever to the unlocked position against the biasing force of the biaser, the locking portion of each lock lever is released from the engagement with the lock grooves to thereby allow the seat and the upper rails to slide relative to the lower rails.